B.A. English & Writing, University of Northern Colorado (2020)
Why does everyone know that the plural of octopus is octopi, but many people seem to think that the plural of borborygmus is borborygmuses?
Because it’s not as common a word.
Everyone knows what sheep are. We see sheep. We count sheep. We talk about sheep from a young age.
But aircraft? We don’t talk about those as much. If we don’t talk about them, it’s harder to have people correct us on the plural. We notice that the plural of “craft” is “crafts” so assume that the plural of “aircraft” is “aircrafts”.
It’s a logical mistake to make, if you’re trying to apply logic to English.
There’s little consistency in English, so it’s weird to assume that because people know the plural of sheep, they’d also know the plural of aircraft. There’s no connection there. I don’t know why knowing the first would lead to knowing the second.
Disabling comments because if one more person tries to correct me on the plural of “octopus” I’m going to scream.
To say that it’s incorrect because it’s etymologically incorrect is fallacious. It’s correct because it has so pervaded common usage as to be considered correct. I know that it’s a Greek word. I know. If people read the comments, they’d see how many times I’d been told that.
But instead, people leave the same repetitive comment because it’s more fun to sound smart than it is to actually help people.
To think— I changed my answer to include the word “octopus” at the last minute. I had originally written “dog” but thought “octopi” was more fun.
Wishes he could read more.
English has inconsistent pluralization conventions:
Mongoose. This one is by far the worst. Mongeese? Mongi? Polygeese? Nope, it’s Mongooses.
Aircraft is a weird word. Depending on context, the word “craft” pluralizes to “craft” or “crafts.” Thus, people get confused and assume that the word always uses the “add and S” pluralization.
The plural of cactus is cactuses, it's a regular count noun!
We think the plural of “aircraft” is “aircrafts” because the plural of “aircraft” is “aircrafts”. There's two categories of plural nouns in English, Counts Nouns which we pluralize, and Noncount Nouns which we don't. Most nouns, like cat, bean, or cow are count nouns. A small group of nouns, like sheep or corn, are noncount nouns. Noncount nouns are irregular.
A process with irregular words called Regularization can occur, in which irregular words become regular. This is very common for words we don't use much, like aircraft or octopus. They both regularize to generic count nouns.
Sheep is used often enough that it is unlikely to regularize, and thus it remains an irregular noncount noun. Aircraft isn't a noncount noun anymore, deal with it.
works at Photography
I’m 65. In my entire life, I have never heard or seen the word “aircrafts” used. Perhaps you are from another country where English is not, for many, the primary language. English is very irregular in many regards, and is a difficult language. It might be argued that English has many dialects, and that “aircrafts” might possibly be an acceptable form in one of those regions.
Lucky to have studied linguistics in high school
… because they haven’t heard “aircraft” used as the plural as often as they’ve heard “sheep” used as the plural.
Really, how many lay people use the word “aircraft?” They use the word “airplane.”
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